This invention relates to a method and apparatus for detecting and processing image information which reads and processes not only image information in frames on an original film, such as negative film, but also the information located on the peripheral areas thereof, such as bar codes provided therein for photographic image handling, so as to discriminate the front surface of the film from back surface of the film or the top of a picture frame from the bottom of the picture frame.
In a photographic printing system it is necessary to measure the density of an original film (for instance, a negative film) in order to determine the printing exposure amount or the correction amount thereof. The average density of a negative film is conventionally measured photographically with respect to its LATD (Large Area Transmittance Density) by using photosensors such as photodiodes provided near the optical path of the optical system used for printing. The negative film is formed by developing a film negative. The LATD method, however, is an image detection technique to photographically measure a negative film generally but not a method to measure the image density of a negative film correctly or across the whole frame. The printing exposure or correction obtained by the LATD measuring method does not therefore quite meet strict requirements. When the negative film is printed on photographic paper, it is necessary to change the exposure amount or the correction amount depending on the size, manufacturer, or sensitivity of the film due to the difference, in light diffusion particular to each film. These differences are conventionally observed and determined visually and inputted manually from a keyboard or determined by a separate device and signals thereof are read out from an information transmission medium. Such key manipulation and signal processing are not only cumbersome but susceptible to errors in inputting.
There has recently been proposed a method which records the name of the film maker and the type of film on each half frame along a longitudinal side of a negative film in the form of bar codes in latent images which are to be imaged after development. FIG. 1A shows an example of the negative film provided with such bar codes. More particularly, perforations 201 and 202 are punched on both sides of the negative film 2 and bar code information 203 is recorded at a predetermined position between the perforations 202 and the edge of the negative film 2 to supply the data, information and so on necessary for printing a frame 204 of the negative film 2. When the negative film 2 is printed by a photographic printer, the bar code information 203 recorded on the negative film 2 is read out by a device such as a bar code reader or a line sensor; a channel is set according to the type of negative film; the image information obtained by measuring the film with the LATD method is processed to determine the exposure amount, and the negative film is finally printed with the thus determined exposure amount. In the prior art, the photographic measurement of frame images 204 on the negative film 2 and the reading out of the bar code information 203 attached thereon are separately conducted while an elongated negative film is being moved. However, the operation involves complicated devices and processing, and hence a solution has long been demanded.
Moreover, it is desired to provide a simple method for readily reading a side belt 206 in a latent image on area of the perforations 202 which is temporarily colored for identification when the type of emulsion is drastically changed, or reading the masking and color balance on the film carrier so as to obtain more information for printing conditions on the negative film 2. Conventional methods have been proposed to output the frame number 205 in latent image of the side prints which are excluded from the information of the bar code 203 at a display unit, or to record the same on a photographic paper 7 corresponding to the frame 204 for facilitating placement of reprinting orders. Those methods, however, are not quite practicable in one way or other.
In typical photographic printing systems, when a negative film is mounted in the system, the front or back surface and the top or bottom direction of the negative film is usually judged visually, which sometimes causes upside down prints or reversed prints. If the negative film is printed on its wrong surface, the printed images are inverted and the printing must be redone. If a frame is printed upside down, it present further problems in determining the printing exposure amount or correction amount. Since the prior art device measures only frame images, it is incapable of detecting and correcting the condition if chronological deterioration occurons an unused film or if the balance in density or color is disturbed due to abnormal development, etc.